The invention relates to the use of a metal organosilicate polymer as an agent for forming a dispersion of a hydrophobic material in water or a dispersion of an organophobic material in an organic solvent.
It relates more particularly to an aqueous dispersion of carbon nanotubes and an aqueous dispersion of benzotriazole, and also to the use of the aqueous dispersion of benzotriazole for the production of a composition for protection against UV radiation.
It is very difficult to disperse particles of hydrophobic compounds in an aqueous phase or to disperse particles of hydrophilic or organophobic compounds in an organic phase.
Many organic compounds are water-insoluble.
This is true of the compounds of the benzotriazole group, and more particularly of 2-(2′-hydroxy-5′-methylphenyl)benzotriazole.
Now, 2-(2′-hydroxy-5′-methylphenyl)benzotriazole consumes the photons emitted by UV rays while at the same time regenerating. It is therefore a molecule which is of great interest for the protection of various elements and supports against UV radiation since it is not consumed by UV irradiation.
However, this molecule is not water-dispersible and cannot be applied simply and in a harmless manner to the elements to be protected.
Carbon nanotubes are, for their part, inorganic materials representative of hydrophobic compounds that are difficult to disperse in water.
In general, in order to obtain a dispersion of carbon nanotubes in water, OH groups are generated at the surface of the carbon nanotubes and then these OH groups are oxidized so as to form carboxylic groups and, finally, they are converted to salts. The nanotubes are then water-“dispersible”.
However, this requires many chemical reactions.
Moreover, a group of compounds referred to equally as metal organosilicate, metal phyllosilicate clay, metal organosilicate polymer or polysilsesquioxane salt, is known.
For example, U.S. Pat. No. 7,132,165 B2 describes the production of compounds of this type from amide surfactants or structuring agents. These compounds are described as being lamellar silica-based mesoporous compounds with high temperature and hydrothermal stability.
These compounds are also described by L. Ukrainczyk et al., in “Template Synthesis and Characterization of Layered Al- and Mg-Silsesquioxanes”, J. Phys. Chem. B 1997, 101, 531-539.
A method for preparing these compounds is described in this document: the silsesquioxane compounds were prepared by precipitation at ambient temperature by adding an aqueous base to a solution of alcohol containing a mixture of AlCl3 or MgCl2 and a trialkoxysilane with n-dodecyl, n-octyl, n-pentyl, 3-methacryloxypropyl, isobutyl or phenyl functionality.
These compounds are described as being usable as absorbent materials, environmental barriers, polymer fillers, catalytic supports or chemical sensors.
Nicola T. Whilton et al., in “Hybrid lamellar nanocomposites based on organically functionalized magnesium phyllosilicate clays with interlayer reactivity”, J. Mater. Chem., 1998, 8(8), 1927-1932, also described the preparation of such compounds by the addition of organotrialkoxysilane to a solution of MgCl2.6H2O in ethanol and precipitation with a sodium hydroxide solution.
However, in this document, no application is described or suggested for these compounds.